The invention relates to a load adjustment device having a throttle valve (9) which determines the output power of an internal combustion engine and is connected, fixed for rotation, with a throttle-valve shaft mounted in a throttle-valve housing. The throttle-valve shaft is acted on by a control element (8a) which cooperates with a driver (4) coupled to an accelerator pedal (1), and is controllable by means of an electric motor (14) cooperating with an electronic control device (17). A displacement path of the driver (4) is limited by an idle stop (LL.sub.max) and, upon application of the driver (4) against the idle stop (LL.sub.max), the control element (8a) is moveable within an idle control range relative to the driver (4) by means of the electric motor (14).
Load adjustment devices which cooperate with carburetors or injection pumps must satisfy the requirement of optimal control of the internal combustion engine over the entire load range. For this, a complicated construction or complicated control is necessary. Thus, carburetors, for instance, in addition to the actual means for forming the air-fuel mixture have additional means such as leaning, starting, idling, accelerating and economizing means, etc. These means complicate the construction of the carburetor and result in increased structural expense in that additional injection nozzles, pumps, special developments of the nozzle needles and separate air feeds are necessary, entirely aside from the high control requirements connected therewith.
Of particular importance in the case of load adjustment devices is control of the state of load of the idling at which only minimum output power is given off by the internal combustion engines while, however, particularly in the case of motor vehicles, there may be loads which require a large amount of power, such as fan, rear window heating, air conditioning, etc. In order to take these possible demands for power into consideration, control of the load adjustment device between a minimum idle position and a maximum idle position is necessary. In the event of failure of the control, an emergency idle position of the setting member or control member must be assured.
In contradistinction to the problem described, load adjustment devices of this type are used, as a general rule, in cases in which the accelerator pedal and the setting member are electronically connected to each other. The accelerator pedal is coupled to the driver and the latter is coupled to the control element. Furthermore, a desired-value detection element which cooperates with the control element and an actual-value detection element which cooperates with the desired-value detection element and acts on the electric setting drive are provided, the electric setting drive being controllable, as a function of the detected values, by the electronic control device.
The electrical connection of accelerator pedal and setting member with the interposed electronic control device makes it possible to set desired-value positions, determined by the accelerator pedal and the driver connected with it. This control is with reference to the actual values resulting from the position of the control element and setting element and serves to test them as to the presence or absence of plausibility conditions. Thereby, in case of the presence or absence of given plausibility conditions, there is the possibility, by means of the electronic control, of effecting a corrective action, by control of the electric setting drive, on the setting element. The setting element may be, for instance, a throttle valve or an injection pump. Thus, for instance, action by the electronic control device in order to avoid wheel slippage upon starting as a result of too much power being given by the gas pedal can be provided. Other automatic controls of the load adjustment device are conceivable, for instance, in the case of automatic shiftings of the transmission, a speed-governing control, or the abovementioned idle control of the internal combustion engine.